FI128740B - Pusher-barge unit, a pusher and a barge - Google Patents

Abstract

The current disclosure relates to an integrated pusher-barge unit (1) comprising a pusher vessel (2) and a barge vessel (3). The pusher-barge unit is characterized in that the pusher vessel (2) is single-hulled and comprises a notch-shaped bow (21), the barge vessel (3) comprises a tapering stern (32), and in that the shapes of the bow (21) of the pusher vessel and the stern (32) of the barge vessel (3) match. The current disclosure further relates to a pusher vessel and to a barge vessel.

Description

PUSHER-BARGE UNIT, A PUSHER AND A BARGE

TECHNICAL FIELD The current disclosure relates to an integrated pusher-barge unit, to a pusher vessel, and to a barge barge vessel.

BACKGROUND Pusher vessels are a type of a tugboat that move cargo vessels by pushing them from the stern of the cargo vessel. A barge is a cargo vessel relying on a separate vessel, such as a pusher or a towboat to maneuver it. A pusher-barge unit comprises a pusher, and a barge that has notch-shaped stern. The pusher is driven to the notch of the barge, attached and the two vessels function as one unit. In articulated pusher- barge combinations (ATB’s), there is some freedom of movement between the vessels, i.e. they can be considered hinged together by attachment pins or the like. However, integrated pusher-barge combinations (ITB's) are rigidly coupled together, and their hulls thus move in concert in all directions. ITB units perform better than ATB’s in rough sea, and are thus preferred in high-sea applications. The problems in current pusher-barge systems relate to the fact that the draft of the barge varies N according to the degree of loading. It is difficult to N accommodate the variable draft of the barge vessel with S the use of a pusher having a single draft. If the S 30 connection between the pusher and the barge allows Ek taking the variable draft into account, the sea-going, * fuel consumption and/or maneuvering properties of the = pusher-barge unit decrease significantly.

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SUMMARY The current disclosure relates to an integrated pusher-barge unit comprising a pusher vessel and a barge vessel. The pusher vessel is single-hulled and comprises a notch-shaped bow, the barge vessel comprises a tapering stern, and the shapes of the bow of the pusher vessel and the stern of the barge vessel match. The unit is characterized in that the notch and the tapering stern are V-shaped.

The current disclosure further relates to a single-hulled pusher vessel. The bow of the pusher vessel 1s notch-shaped for fitting a tapering stern of a barge vessel into the notch, and the pusher vessel comprises coupling means for coupling the stern of the barge vessel rigidly into the notch for forming an integrated pusher-barge unit. The pusher vessel is characterized in that the notch is V-shaped.

The current disclosure further relates to a barge vessel. The stern of the barge vessel is tapering for fitting the stern into a notch-shaped bow of a pusher vessel, and the barge vessel comprises complementary coupling means for coupling the stern of the barge vessel rigidly into the notch of a pusher vessel for forming an integrated pusher-barge unit, wherein the complementary coupling means is configured to allow coupling the pusher vessel to the barge vessel at more o than one height to accommodate variable drafts of the N barge vessel. The barge vessel is characterized in that 5 the tapering stern is V-shaped.

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N BRIEF DESCRIPTION OF THE DRAWINGS

I n. The accompanying drawings, which are included to O provide a further understanding of the current 3 disclosure and constitute a part of this specification, > 35 illustrate embodiments of the disclosure and together with the description help to explain the principles of the current disclosure. In the drawings: Fig. 1 is a schematic presentation of a prior-art pusher-barge unit.

Fig. 2 is a schematic illustration of an embodiment of a pusher-barge unit according to the current disclosure. Panels A to C depict the constant draft of the pusher vessel and the variable draft of the barge vessel.

Fig. 3 is a schematic illustration of an embodiment of a pusher-barge unit according to the current disclosure. Panel A depicts the pusher-barge unit from above, and panel B from below.

Fig. 4 is a perspective view of an embodiment of a pusher and a barge according to the present disclosure from above. Panel A depicts the coupling means of the pusher vessel, and panel B the complementary coupling means of the barge vessel. Panel C depicts the engaged pusher and the barge as a unit.

Fig. 5 is a perspective view of an embodiment of a pusher-barge unit according to the current disclosure from below depicting the structures of the separated vessels.

Fig. 6 depicts various shapes of the barge vessel stern seen from one side.

Fig. 7 depicts various shapes of the pusher vessel bow as seen from below.

S

N DETAILED DESCRIPTION In one aspect, an integrated pusher-barge unit N comprising a pusher vessel and a barge vessel is z disclosed. The pusher vessel is single-hulled and o comprises a notch-shaped bow, the barge vessel comprises 15 a tapering stern, and the shapes of the bow of the pusher = 35 vessel and the stern of the barge vessel match. The N integrated pusher-barge unit is characterized in that the notch and the tapering stern are V-shaped.

In another aspect, a single-hulled pusher vessel is disclosed. The bow of the pusher vessel is notch- shaped for fitting a tapering stern of a barge vessel into the notch, and the pusher vessel comprises coupling means for coupling the stern of the barge vessel rigidly into the notch for forming an integrated pusher-barge unit. The single-hulled pusher vessel is characterized in that the notch is V-shaped.

In yet another aspect, a barge vessel is disclosed. The stern of the barge vessel is tapering for fitting the stern into the notch of the bow of a pusher vessel, and the barge vessel comorises complementary coupling means for coupling the stern of the barge vessel rigidly into the notch of a pusher vessel for forming an integrated pusher-barge unit, wherein the complementary coupling means is configured to allow coupling the pusher vessel to the barge vessel at more than one height to accommodate variable drafts of the barge vessel. The barge vessel is characterized in that the tapering stern is V-shaped.

An advantage of the current pusher-barge unit may be that the pusher-barge unit can be efficiently used both when the barge is fully loaded and empty. It may be possible to design a pusher-barge unit which has reasonable water resistance and running properties at various drafts. This may bring advantages in the x reduction of fuel consumption, and in allowing more N flexibility to the transport of the barge vessels. This S 30 way, the barge vessels may be used more efficiently, Q leading to capital savings. =E Another advantage is the possibility to omit * ballast water system from the barge vessel. Ballast = water is used to increase the draft of a barge vessel o 35 when it is unloaded, or carries only a light load. S Ballast water may carry invading species, and therefore maritime regulations require a ballast water management system to avoid the distribution of species across oceans. Such systems are expensive, need maintenance and may increase the using costs of a barge vessel.

5 The pusher vessel and the barge vessel are configured to co-operate as a single unit. The current pusher-barge unit may be usable with barge vessels of various design. The barge vessel may be a small river vessel. Alternatively, large sea-going vessels of 10,000 dwt or even larger may be used. The barge vessel may be designed to carry various types of cargo. It may be a bulk barge, tanker, roro, or a general cargo barge. Although the pusher vessel and the barge vessel are detachable from each other, the actual cargo- transporting operation is performed with the vessels attached to each other. The pusher vessel and the barge vessel are attached to each other rigidly, so that there is as little as possible movement between the pusher vessel and the barge vessel. In other words, the current disclosure relates to an integrated pusher-barge unit. The steering and navigation equipment for maneuvering the pusher-barge unit is located at the pusher vessel. However, some components, such as side or bow propellers, navigation lights etc. may be positioned on the barge vessel. Typically, they are steered from the pusher vessel, which may contain the bridge of the pusher-barge unit. The necessary N electrical and other connections between the pusher N vessel and the barge vessel may me designed as known in S 30 the art. Q The pusher-barge unit may be remotely- Ek controllable or autonomous. A remotely-controllable or * autonomous vessel may be controllable from both a remote = location and from a bridge present on the vessel. o 35 S By a notch-shaped bow is meant that the bow contains a notch, which is wide enough for the stern of the barge vessel to fit into it. Further, to ascertain a rigid enough connection between the pusher vessel and the barge vessel, the notch needs to be deep enough, and its sides strong enough. The skilled person determines such characteristics according to design methods known in the art. By depth of the notch is herein meant the distance that the notch extends towards the stern of the pusher vessel from the frontmost tip of the bow. The notch comprises two edges at the sides of the pusher vessel, two sides that comprise contact surfaces (i.e. the surfaces becoming adjacent to the surface of the barge vessel), and an end (i.e. the deepest position of the notch). The edges of the notch may be pointed, i.e. resemble a regular bow of a ship, or they may be blunt.

This means that the notch may now extend all the way to the side of the pusher vessel.

The shape of the bow can be described as being a twin bow. This means that the notch in the bow extends along the whole vertical length of the pusher hull.

However, the pusher is a single-hulled vessel, i.e. the lowest point of the hull is in the middle of its cross- section. In other words, the vessel is designed to run as a single body in water, not as two bodies separated by an above-water portion.

The surfaces of the notch and the corresponding taper of the bow i.e. the contact surfaces, may be vertical. However, embodiments may be envisaged in which N the surfaces are slanting.

N The stern of the barge vessel may be tapering only S 30 in the horizontal direction. In other words, the barge Q vessel does not taper from the bottom and from the top =E more than is customary in ship building, but only * becomes narrower. The stern of the barge vessel thus = forms a horizontal wedge that is configured to fit into o 35 the matching bay of the pusher vessel.

S The end of the notch (i.e. the deepest position of the notch) may be a vertical. It may alternatively be oblique, or contain oblique portions. Also curving profile of the end in the vertical direction is possible. The main purpose of the pusher vessel is to provide propulsion to the barge vessel. Therefore, to keep the length of the pusher-barge unit as short as possible, it may be advantageous to design the pusher vessel to contain as deep a notch as possible relative to its length. This may have the additional advantage that the forces exerted on the two vessels by maneuvering or weather conditions, such as wind and rough sea, are distributed over a larger area of the hulls.

In one embodiment of the pusher-barge unit, the depth of the notch is at least one third of the length of the pusher vessel. In one embodiment of the pusher vessel, the depth of the notch is at least one third of the length of the pusher vessel. In one embodiment of the pusher vessel, the depth of the notch is at least half of the length of the pusher vessel.

It is thus possible that the notch extends to the stern side of the bow structures. The notch may thus be a dominant element in the appearance of the pusher vessel. In this specification, a notch thus means the bay into which the stern of the barge vessel is configured to be caught, irrespective of the size, as N long as the barge vessel may be maneuvered through the N connection.

S 30 Q In another embodiment of the pusher-barge unit, Ek the depth of the notch is at least half of the length * of the pusher vessel. By the depth of the notch is meant = the distance from the bow-end of the notch to the stern o 35 end. In other words, the depth is measured along the S longitudinal axis of the pusher vessel from the edge of the notch to its end. The tapering stern of the barge vessel typically extends the same distance as the notch. As the shapes of the notch and the tapering stern match, this mean that the vessels are of the same width.

The shapes of the bow of the pusher vessel and the stern of the barge vessel match. In other words, the bow of the pusher vessel and the stern of the barge vessel have complementary shapes. When the two vessels are coupled to each other, the contact surfaces of the pusher vessel and the barge vessel may be in close proximity to each other. They may touch at least in some areas. This means that the bow of the pusher vessel and the stern of the barge vessel have corresponding shapes. The matching of the surfaces does not need to be equally accurate in all areas. Embodiments may be envisaged in which there are certain areas on the contact surfaces that are designed to be further away from each other than in some other areas. It may be advantageous, for example, to design these areas to accommodate various eguipment, such as anchors, navigation lights, etc. In on embodiment of the pusher-barge unit, the draft of the pusher vessel is constant, and the smallest draft of the barge vessel is configured to be the same or larger that the draft of the pusher vessel hull. In other words, the barge vessel swims deeper than the pusher when the barge vessel is carrying a load. When N the barge vessel is not carrying a load, it may swim N deeper than the pusher vessel, or it may swim at an S 30 egual depth with the pusher vessel. Some types of barge Q vessels, such as container barges, are practically never Ek transported completely unloaded. It may be advantageous * to design the pusher-barge unit so that the drafts of = the pusher vessel and cargo vessel hulls are the same o 35 with the minimum expected load. Therefore, in situations S when the barge vessel is completely empty, the barge vessel may swim higher than the hull of the pusher vessel.

The minimum expected load may be either cargo or ballast material.

However, other types of vessels, such as bulkers or tankers, may travel empty as a part of their normal operation.

Therefore, for such vessels it may be advantageous to have the two vessels swim at the same draft when the barge vessel is completely empty.

The hull defines the base line of the vessel shape.

Thus, the propulsion of the pusher vessel, for example the thrusters or skegs or other appendages may extend below the actual hull of the pusher.

However, when the barge vessel is fully loaded, the propulsion should not extend below the hull of the barge vessel.

When the barge is unloaded, its draft may be smaller than that of the pusher vessel propulsion.

It is, however, naturally possible to have an embodiment, in which the thrusters or the like do not extend below the hull (i.e. the baseline) of the pusher.

If the pusher vessel is designed to have a constant draft, the fuel economics and speed of the pusher-barge unit may be optimized, since at least the major propulsion devices of the pusher-barge unit may be located in the pusher vessel.

To reduce the flow resistance of the pusher-barge unit, it may be advantageous to have the barge vessel to have at least the same draft as the pusher vessel.

For example, when Q the barge vessel is unloaded, i.e. it is at its lightest, N it may have the same draft as the pusher vessel hull.

S 30 When the barge vessel carries the maximum load, i.e. it Q is at its heaviest, its draft is larger than that of the Ek pusher vessel hull.

Such arrangement might allow + advantageous water flow, since there are no protruding = structures to obstruct water flow during the pusher- o 35 barge unit movement.

Additionally, the combination of S the notch-shaped bow of the pusher vessel with the deep-

running configuration of the barge vessel provides surprising advantages compared to prior art. Especially in situation where the barge vessel has a larger draft than the pusher vessel hull, prior art arrangement with the notch in the stern of the barge vessel creates significant water resistance. Instead of continuing to flow along the bottom of the pusher vessel, the water eddies at the junction of the two vessels. Even if the shapes of the vessels are designed to closely match, the difference in draft will inevitably cause inefficiencies.

The coupling of the pusher vessel and the barge vessel 1s done by coupling means. Various types of coupling means are known in the art. One way of establishing a connection is to use pins in one vessel, and matching sockets in the other. The sockets may be, for example sunken into the hull of the vessel, or be attached on the outside of the hull. Alternatively, other types of coupling means, such as complementary and lockable horizontal rib structures may be used to couple the vessels together.

In one embodiment of the pusher-barge unit, the pusher vessel and the barge vessel comprise coupling means that are configured to allow coupling the two vessels into a pusher-barge unit at more than one relative draft. The coupling means are designed to allow the vessels to be coupled together at all drafts of the x barge vessel. As the draft of the pusher vessel remains N constant, in some embodiments it may be advantageous to S 30 have the coupling means on the pusher vessel at a fixed Q position, whereas the counterparts on the barge vessel Ek may be adjustable and/or they may be present on more * than one height. = The two vessels are coupled to each other o 35 reversibly, so that the connection is rigid and durable S as long as needed, but can be detached when necessary. Thus, for example when one barge vessel is being loaded or unloaded, the pusher vessel can already retrieve another barge vessel for transport.

In one embodiment of the pusher-barge unit, the bottom of the hull of both the pusher vessel and the barge vessel is flat for the majority of the length of each vessel. A flat bottom may have the advantage that the transition point between the two vessels may be easier to design. In other words, the bottoms of both the pusher vessel and the barge vessel may be flat at the point where the two vessels are in contact.

In one embodiment of the pusher-barge unit, the notch and the tapering stern are V-shaped. If the notch and the corresponding tapering stern are V-shaped, the end of the notch and the corresponding tapering stern may be rounded. A suitable design is selected by the skilled person in view of, for example, strength and practical construction aspects. Also the type of couplings used to connect the pusher vessel and the barge vessel together may influence the most suitable shape of the end. In a V-shaped notch, the width of the notch decreases steadily from the bow towards the stern of the pusher vessel. In a U-shaped notch, the width of the notch remains constant for a predetermined length from the bow. The end (i.e. the bottom) of the notch may be sharp or rounded.

The water flows along the sides of the barge N vessel, and along the taper to continue under the pusher N vessel. The position on each side of the barge vessel, S 30 at which the taper begins, is termed an aft shoulder or Q a knuckle. The aft shoulder may be rounded for smooth =E water flow. To avoid flow separation at the beginning * of the taper at the stern of the barge vessel (i.e. at = the knuckle), the taper may have an overall angle of 20° o 35 relative to the barge vessel side. However, to keep the S length of the taper appropriate, a larger angle of, for example, 30° and up to 40° may be used. The larger the angle, the more advantageous it may be to have a rounded aft shoulder so that the angle increases gradually along a pre-determined length of the hull. The radius of the rounding at the aft shoulder may be at least 0.4 x 1, L being the length of the barge vessel. The rounding may be, for example at least 0.6 x L or 0.65 x L.

To avoid flow separation at the aft shoulder, vortex generators may be placed on the hull of the barge vessel. Their design and position are known to the skilled person. Although they are designed to produce vortexing, the overall water resistance created at the aft shoulder may be reduced through reduced risk of flow separation.

The embodiments described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment. The pusher-barge unit, the pusher vessel and the barge vessel to which the disclosure is related, may comprise at least one of the embodiments described hereinbefore.

DRAWINGS Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

The description below discloses some x embodiments in such a detail that a person skilled in N the art is able to utilize objects of the disclosure S 30 based on this specification. Not all features of the S embodiments are discussed in detail, as many of them =E will be obvious for the person skilled in the art. * Item numbers will be maintained in the = following exemplary embodiments in the case of repeating o 35 components. The figures are not drawn to scale, and many S features of the pusher-barge unit not necessary to understand the system have been omitted for clarity.

Figure 1 depicts a prior-art pusher-barge unit.

The stern 32 of the barge vessel 3 comprises a notch for the pusher 2. The bow 21 of the pusher vessel 2 (not visible) approximately matches the shape of the notch.

The arrows indicate the flow of water into the gap between the two vessels.

Such flow may cause eddying and turbulence that cause resistance to the movement of the pusher-barge unit.

The effect of the vessel shapes

Figure 2 depicts a pusher-barge unit 1 according to the present disclosure.

Panel A presents the unit 1 with a fully loaded barge vessel 3, panel B with a barge 3 having an intermediate load, and panel C with an empty barge 3. The wavy line depicts water level.

Especially the pusher vessel 2 has been drawn in a very simplistic manner.

In addition to the features depicted in figure 2, the pusher vessel 2 may comprise antennas and masts that are used in navigation.

All such details have been omitted for clarity, but they may be present, especially in further automated systems, such as autonomous vessels.

The stern 22 and the propulsion 25 of the pusher vessel 2 are indicated in the figure.

Although figure 2 is not drawn to scale, it the length difference between the pusher vessel 2 and the barge vessel 3 can be seen to be significant.

The current pusher-barge unit 1 may offer advantages especially in N case of large barge vessels 3, since their capital cost N per unit is large, and their efficient routing and S 30 handling may provide considerable monetary savings.

S Additionally, even small relative improvements in the =E sea-going ability of the vessels may bring about + substantial energy savings, and corresponding lowering = of environmental impacts. o 35 The barge vessel may be any type of a barge S vessel known in the art for transporting cargo.

Examples of such are tanker barges, designed for oil, LNG, fuel,

water, juice, molasses and the like. Bulker barges carry mainly dry cargo, such as ore, grain, scrap metal, coal etc.

The draft 23 of the pusher vessel 2 and the draft 33 of the barge vessel 3 are depicted in each panel. Although the figure is not drawn to scale, the scale bars 23, 33, have been drawn to allow comparing the relative drafts of the vessels 2,3 in each panel. It can be seen that the draft 23 of the pusher vessel 2 remains constant in all panels, whereas the draft of the barge vessel decreases from panel A to panel C, i.e. according to the reduction in the degree of loading. When the barge vessel 3 is loaded, its draft is larger than that of the pusher vessel 2 (panels A and B). When the barge vessel 3 is unloaded, the drafts of the two vessels are approximately the same. In the embodiment of figure 2, the barge vessel’s draft is visualized as being slightly larger, still, but this does not necessarily need to be the case. In some embodiments, the drafts 23, 33 may be egual when the barge vessel 3 is unloaded.

The pusher vessel 2 is in contact with the stern 32 of the barge vessel 3 with its bow 21. In the viewing direction of figure 2, it can be seen that the stern 32 of the barge vessel 3 is behind the profile of the pusher vessel 2. The notch is not visible from this viewing direction, but the relative positions of the two N vessels indicate the depth of the notch. In this N embodiment, the notch is approximately half the length S 30 of the pusher vessel 2.

S As the bow 21 of the pusher vessel 2 and the Ek stern 32 of the barge vessel 3 are designed to have * matching shape, it can be deduced from figure 2 that the = end of the notch is not exactly vertical. Instead, the o 35 notch is deeper at the bottom 24 of the pusher vessel 2 S than at the deck side. Correspondingly, the stern 32 of the barge vessel 3 is shaped obliquely, and the vessel 3 is longer at the bottom 34 than at the deck level. Figure 3, panels A and B depicts the pusher- barge unit 1 according to the present disclosure from above and below, respectively. This viewing direction illustrates the shape of the notch. The bow 21 of the pusher vessel 2 is divided into two parts, which are separated by the notch. The notch functions as a bay for the stern 32 of the barge vessel 3.

The notch has approximately the shape of a V, and its end 211, i.e. the bottom, is sharp. However, embodiments can be envisaged in which the end 211 of the notch is rounded. The end 211 of the notch is in the middle of the pusher vessel 2. The notch is defined by two symmetrical sides 212, whose width decreases towards an edge 214. The two-part bow 21 of the pusher vessel 2 ends at two edges 214, which are located at the level of the side of the vessel 2. The edges 214 of the bow 21 define the end-points of the notch sides 212, i.e. the tips of the double bow 21.

The sides 212 narrow linearly along the majority of the length of the notch towards the edge

214. It is possible that the narrowing is linear throughout the length of the notch. However, in the embodiment of fig. 3, the sides 212 are slightly curved closer to the edge 214 of the notch. Practical N manufacturing aspects, for example, may determine the N exact shape of the notch. The curvature may have a radius S 30 greater than 0.6 x 1, wherein L is the length of the S barge vessel. Such dimensioning may avoid flow I separation at stern of the barge vessel, which may * decrease the drag caused by the water flow around the = stern of the barge vessel. o 35 The stern 32 of the barge vessel 3 has a S complementary shape to that of the notch. Thus, it contains a taper that fits into the notch of the pusher vessel 2. The taper could have an angle of approximately 20° relative to the side of the barge vessel to avoid flow separation at the beginning of the taper (i.e. the knuckle). However, for many applications, such an angle may lead to an impractically long taper.

Therefore, a larger angle of, for example 25° 30° or even 35° may be used.

In this embodiment, the taper has the same length as the notch.

The taper comprises an aft shoulder 324, which is the point at which the taper begins.

The stern 32 also contains and end 321, which is the back- most part of the stern 32. When the pusher vessel ? and the barge vessel 3 are coupled to each other, the aft shoulders 324 of the taper are positioned at the edges 214 of the notch.

The sides 212 of the notch increase in width as the width of the taper 322 decreases.

The end 321 of the taper is positioned at the end 211, i.e. the bottom, of the notch.

In this embodiment, the pusher vessel 2 and the barge vessel 3 have approximately the same width, notwithstanding the taper at the stern 32 of the barge vessel 3. At a given point along the length of the notch, and the corresponding taper, the combined width of the two sides 212 of the pusher vessel 2 and the taper 322 of the barge vessel 3 equal the width of the pusher- barge unit 1. In panel B, the flat portion of the bottoms 24, N 34 of each vessel 2, 3 is depicted (the thinner line in N Fig. 3B). The flat portions have the same size, which S 30 may be beneficial for the water flow around the hull of Q the vessels 2, 3. The propulsion 25 is located at the Ek stern 22 of the pusher vessel 2. Although only two * propellers are indicated in figure 3, any number and = design of a propulsion system known in the art is in o 35 principle possible in a pusher-barge unit 1 according S to the present disclosure.

It is further possible that there are propellers, jets or other propulsion means also on the barge vessel 3. Figure 4 is a perspective view of the pusher- barge unit 1 according to the present disclosure. Panel A depicts the pusher-barge unit 1 from above, and panel B from below. In panel A, the parts of the pusher vessel 2 bow 21 and the barge vessel 3 stern 32 are visible in more detail. The end of the notch 211 and the end of the taper 321 are next to each other. In panel B, it can be seen that the end of the taper 321 is the vertical “blade” of the stern.

In figure 4, the barge vessel 3 swims deeper than the pusher vessel 2. In other words, its draft is larger than that of the pusher vessel 2. The bottom 24 of the pusher vessel 2 comprises a flat portion and a slanted portion towards the stern 22 of the pusher vessel 2. The propulsion 25 is located on the slanted portion.

The pusher vessel 2 and the barge vessel 3 have the same width, i.e. the edge of the notch 214 and the aft shoulder 324 form a continuous surface for the water to flow along. This helps to reduce the water resistance to the vessel movement. Since the barge vessel 3 has a larger draft than the pusher vessel 2, there is a step at the junction point between the two vessels 2,3. However, there is no cavity that would cause eddying of N the water (cf. prior art in fig. 1). On the contrary, N the water flows along the sides of the barge vessel 3 S 30 under the pusher vessel 2. In prior art, avoidance of Q such cavity would necessitate having the pusher vessel I and the barge vessel to have the same draft, which would * either mean having the pusher vessel run with variable = draft, or using ballast water to keep the draft of the o 35 barge vessel constant.

o

N

Figure 5 depicts the pusher vessel 2 and the barge vessel 3 when they are detached. The coupling means 4 is schematically presented. Panel A shows the inside of the notch, and panel B the structure of the stern 32 of the barge vessel 3. The structures of the bow 21 of the pusher vessel 2 and the stern 32 of the barge vessel 3 are similar to figures 2 to 4. The V-shaped notch comprises two sides 212, each of which extends to a vertical edge 214 in the bow-end, and to a common end 211 at the stern- end. Although in the embodiment of figure 5, the edges 214 are vertical, it may improve the maneuvering properties of the pusher vessel 2 to have each edge 214 of the bow 21 to tilt forward, i.e. the upper part of the edge 214 is further forward than the lower part (i.e. as is common in marine vessel bows). On the inside of the notch, each side 21 comprises a contact surface 213. In the embodiment of figure 5, the contact surfaces 213 are vertical and straight, apart from the curvature close to the edge

214. Also the end 211 is straight. However, it is possible that the surfaces are obligue. For example, the Upper part of the contact surfaces 213 may be protruding compared to the lower part. Panel 5A depicts the coupling means 4 on the pusher vessel 2 side. In this embodiment, the coupling means comprises three pins 41. The pins are configured N to be insertable to corresponding sockets 42 on the N barge vessel 3. All pins 41 are in a single horizontal S 30 line. One pin 41 being located at the end 211 of the Q notch, while the two others are symmetrically positioned I on each contact surface 213. The pins 41 and/or the * sockets 42 comprise locking means allowing to secure the = vessels together while the pusher-barge unit is used. o 35 The locking means also comprises suitable releasing S means so that the vessels can be detached as desired.

The locking means and the releasing means are not depicted in the figure, and can be designed as is known in the art. Panel 5B depicts the structures of the barge vessel 3 stern 32. The stern comprises a tapering having aft shoulders 324, which are the points on each side of the barge vessel 3 at which the stern 32 begins to narrow. Due to the symmetrical design of the stern 32, the aft shoulders 324 are positioned at the same points along the length of the barge vessel 3. Each side of the Laper comprises a contact surface 323, which is designed to be in close proximity or in contact with the corresponding contact surface 213 of the pusher vessel 2, when the vessels are coupled. The two contact surfaces 213, 323 have matching shapes. The taper of the barge vessel 3 stern 32 comprises an end 321, which is a vertical "ridge” designed to be in close proximity or in contact with the end 211 of the notch, when the vessels are coupled. The coupling means 4 of the barge vessel 3 comprise sockets 42. They are designed to receive the pins 41 of the pusher vessel 2. They are in corresponding positions to the pins 41 on each contact surface 323 and at the end 321 of the taper. However, at each location, there are several sockets 42 in a vertical row. This allows the pins 41 of the pusher vessel 2 to make contact with the sockets 42 at various drafts of the barge vessel

3. N In the embodiment of figure 5, there are five N sockets in a vertical row at each of the three positions. S 30 However, the number of the sockets may be selected for Q each application by the skilled person. The number of Ek the sockets 42 and interval between them determines the * accuracy at which the draft difference between the = vessels 2, 3 can be taken into account in coupling the o 35 vessels together. S As described above, the coupling means 4 may comprise locking and releasing means (not depicted) to regulate the attachment and detachment of the vessels 2, 3 to each other. Further, the sockets 42 and/or the pins 41 can be shaped to simplify the insertion of the pins 41 into the sockets 42. For example, the sides of the sockets 42 may be rounded to make the opening funnel- shaped.

Figure 6, panels A to D, depicts various embodiments of the barge vessel 3 stern 32. Coupling means are omitted from the figure.

In panel A, the end 321 of the stern 32 is oblique in the forward direction. In other words, the stern 32 at waterline is further back than higher up along the end 321. The end itself is straight.

In panel B, the end 321 is straight and vertical, whereas in panel C it is oblique backwards. Thus, in this embodiment, the stern 32 at waterline is shorter than higher up along the end 321.

In panel D, a similar embodiment to panel C is depicted, with the difference that the end 321 is not straight. In the embodiment depicted in panel D, the lower part of the end 321 is vertical, but the end 321 then arches into an outwardly extending stern. Other curved structures can be envisaged.

Figure 7, panels A to C depicts various shapes of the notch as seen from below.

N In panel A, the notch has a straight V-shape, N and the contact surface 213 of each side 212 of the S 30 notch are straight from the bottom 211 to the edge 214 Q of the notch. Especially in such embodiments, it may be Ek advantageous to achieve an angle close to 20° the side * of the barge and the taper. A small taper angle would = be reflected in a correspondingly slowly increasing o 35 width of the side of the notch 212. S In panel B, a U-shaped notch is depicted. In the embodiment of panel B, the edges 214 of the notch are blunt, but they could alternatively thin. A thinner edge 214 may be advantageous in designing smooth joint between the pusher vessel 2 and the barge vessel 3 (not shown) to ascertain smooth water flow along the sides. The contract surfaces 213 are arched for most of their areas.

In panel C, the edges 214 of the notch are also blunt, but in this embodiment rounded. The notch is primarily V-shaped, but each contact surface 213 contains rounding to accommodate the rounded aft shoulder of the barge vessel 3.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.

oO

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O N

Claims (10)

1. An integrated pusher-barge unit (1) comprising a pusher vessel (2) and a barge vessel (3), wherein the pusher vessel (2) is single-hulled and comprises a notch-shaped bow (21), the barge vessel (3) comprises a tapering stern (32), and the shapes of the bow (21) of the pusher vessel and the stern (32) of the barge vessel (3) match, characterized in that the notch (21) and the tapering stern (31) are V-shaped.

2. The integrated pusher-barge unit (1) according to claim 1, characterized in that the draft (23) of the pusher vessel (2) is constant, and the smallest draft (33) of the barge vessel (3) is configured to be the same or larger that the draft (23) of the pusher vessel hull (2).

3. The integrated pusher-barge unit (1) according to claim 1 or 2, characterized in that the pusher vessel (2) and the barge vessel (3) comprise coupling means (4) that are configured to allow coupling the two vessels into a pusher-barge unit (1) at more than one relative draft.

4. The integrated pusher-barge unit (1) according to claim 1 or 2, characterized in that the bottom (24, 34) of the hull of both the pusher vessel (2) and the barge vessel (3) is flat for the majority of the length of each vessel. o

5. The integrated pusher-barge according to O any of the preceding claims, characterized in <+ that the depth of the notch (21) is at least one third = 30 of the length of the pusher vessel (2). N

6. The integrated pusher-barge according to E any of the preceding claims, characterized in o that the depth of the notch (21) is at least half of the 15 length of the pusher vessel (2). = 35

7. A single-hulled pusher vessel (2), the bow N of the pusher vessel (2) being notch-shaped (21) for fitting a tapering stern (31) of a barge vessel (3) into the notch (21), and the pusher vessel (2) comprising coupling means for coupling the stern of the barge vessel (3) rigidly into the notch for forming an integrated pusher-barge unit (1), characterized in that the notch (21) is V- shaped.

8. The pusher vessel (2) according to claim 7, characterized in that the depth of the notch (21) is at least one third of the length of the pusher vessel (2).

9. The pusher vessel (2) according to claim 7 or 8, characterized in that the depth of the notch (21) is at least half of the length of the pusher vessel (2).

10. A barge vessel (3), the stern (32) of the barge vessel (3) being tapering for fitting the stern (32) into the notch (21) of the bow of a pusher vessel (2), and the barge vessel (3) comprising complementary coupling means for coupling the stern of the barge vessel (3) rigidly into the notch of a pusher vessel (2) for forming an integrated pusher-barge unit (1), wherein the complementary coupling means is configured to allow coupling the pusher vessel (2) to the barge vessel (3) at more than one height to accommodate variable drafts (33) of the barge vessel (3), characterized in that the tapering stern (31) is V-shaped. oO

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